/****************************************************************************
 *
 * Copyright 2016 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/
/*
 * Copyright (c) 2002 CITEL Technologies Ltd.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of CITEL Technologies Ltd nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY CITEL TECHNOLOGIES AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL CITEL TECHNOLOGIES OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * This file is a contribution to the lwIP TCP/IP stack.
 * The Swedish Institute of Computer Science and Adam Dunkels
 * are specifically granted permission to redistribute this
 * source code.
*/

/**
 * @file
 * IGMP - Internet Group Management Protocol
 *
 */

/*-------------------------------------------------------------
Note 1)
Although the rfc requires V1 AND V2 capability
we will only support v2 since now V1 is very old (August 1989)
V1 can be added if required

a debug print and statistic have been implemented to
show this up.
-------------------------------------------------------------
-------------------------------------------------------------
Note 2)
A query for a specific group address (as opposed to ALLHOSTS)
has now been implemented as I am unsure if it is required

a debug print and statistic have been implemented to
show this up.
-------------------------------------------------------------
-------------------------------------------------------------
Note 3)
The router alert rfc 2113 is implemented in outgoing packets
but not checked rigorously incoming
-------------------------------------------------------------
Steve Reynolds
------------------------------------------------------------*/

/*-----------------------------------------------------------------------------
 * RFC 988  - Host extensions for IP multicasting                         - V0
 * RFC 1054 - Host extensions for IP multicasting                         -
 * RFC 1112 - Host extensions for IP multicasting                         - V1
 * RFC 2236 - Internet Group Management Protocol, Version 2               - V2  <- this code is based on this RFC (it's the "de facto" standard)
 * RFC 3376 - Internet Group Management Protocol, Version 3               - V3
 * RFC 4604 - Using Internet Group Management Protocol Version 3...       - V3+
 * RFC 2113 - IP Router Alert Option                                      -
 *----------------------------------------------------------------------------*/

/*-----------------------------------------------------------------------------
 * Includes
 *----------------------------------------------------------------------------*/

#include <net/lwip/opt.h>

#if LWIP_IGMP					/* don't build if not configured for use in lwipopts.h */

#include <net/lwip/ipv4/igmp.h>
#include <net/lwip/debug.h>
#include <net/lwip/def.h>
#include <net/lwip/mem.h>
#include <net/lwip/ipv4/ip.h>
#include <net/lwip/ipv4/inet_chksum.h>
#include <net/lwip/netif.h>
#include <net/lwip/ipv4/icmp.h>
#include <net/lwip/udp.h>
#include <net/lwip/tcp.h>
#include <net/lwip/stats.h>

#include <string.h>

/*
 * IGMP constants
 */
#define IGMP_TTL                       1
#define IGMP_MINLEN                    8
#define ROUTER_ALERT                   0x9404U
#define ROUTER_ALERTLEN                4

/*
 * IGMP message types, including version number.
 */
#define IGMP_MEMB_QUERY                0x11	/* Membership query         */
#define IGMP_V1_MEMB_REPORT            0x12	/* Ver. 1 membership report */
#define IGMP_V2_MEMB_REPORT            0x16	/* Ver. 2 membership report */
#define IGMP_LEAVE_GROUP               0x17	/* Leave-group message      */

/* Group  membership states */
#define IGMP_GROUP_NON_MEMBER          0
#define IGMP_GROUP_DELAYING_MEMBER     1
#define IGMP_GROUP_IDLE_MEMBER         2

/**
 * IGMP packet format.
 */
#ifdef PACK_STRUCT_USE_INCLUDES
#include <net/lwip/arch/bpstruct.h>
#endif
PACK_STRUCT_BEGIN struct igmp_msg {
	PACK_STRUCT_FIELD(u8_t igmp_msgtype);
	PACK_STRUCT_FIELD(u8_t igmp_maxresp);
	PACK_STRUCT_FIELD(u16_t igmp_checksum);
	PACK_STRUCT_FIELD(ip_addr_p_t igmp_group_address);
} PACK_STRUCT_STRUCT;
PACK_STRUCT_END
#ifdef PACK_STRUCT_USE_INCLUDES
#include <net/lwip/arch/epstruct.h>
#endif
static struct igmp_group *igmp_lookup_group(struct netif *ifp, ip_addr_t *addr);
static err_t igmp_remove_group(struct igmp_group *group);
static void igmp_timeout(struct igmp_group *group);
static void igmp_start_timer(struct igmp_group *group, u8_t max_time);
static void igmp_delaying_member(struct igmp_group *group, u8_t maxresp);
static err_t igmp_ip_output_if(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest, struct netif *netif);
static void igmp_send(struct igmp_group *group, u8_t type);

static struct igmp_group *igmp_group_list;
static ip_addr_t allsystems;
static ip_addr_t allrouters;

/**
 * Initialize the IGMP module
 */
void igmp_init(void)
{
	LWIP_DEBUGF(IGMP_DEBUG, ("igmp_init: initializing\n"));

	IP4_ADDR(&allsystems, 224, 0, 0, 1);
	IP4_ADDR(&allrouters, 224, 0, 0, 2);
}

#ifdef LWIP_DEBUG
/**
 * Dump global IGMP groups list
 */
void igmp_dump_group_list(void)
{
	struct igmp_group *group = igmp_group_list;

	while (group != NULL) {
		LWIP_DEBUGF(IGMP_DEBUG, ("igmp_dump_group_list: [%" U32_F "] ", (u32_t)(group->group_state)));
		ip_addr_debug_print(IGMP_DEBUG, &group->group_address);
		LWIP_DEBUGF(IGMP_DEBUG, (" on if %p\n", group->netif));
		group = group->next;
	}
	LWIP_DEBUGF(IGMP_DEBUG, ("\n"));
}
#else
#define igmp_dump_group_list()
#endif							/* LWIP_DEBUG */

/**
 * Start IGMP processing on interface
 *
 * @param netif network interface on which start IGMP processing
 */
err_t igmp_start(struct netif *netif)
{
	struct igmp_group *group;

	LWIP_DEBUGF(IGMP_DEBUG, ("igmp_start: starting IGMP processing on if %p\n", netif));

	group = igmp_lookup_group(netif, &allsystems);

	if (group != NULL) {
		group->group_state = IGMP_GROUP_IDLE_MEMBER;
		group->use++;

		/* Allow the igmp messages at the MAC level */
		if (netif->igmp_mac_filter != NULL) {
			LWIP_DEBUGF(IGMP_DEBUG, ("igmp_start: igmp_mac_filter(ADD "));
			ip_addr_debug_print(IGMP_DEBUG, &allsystems);
			LWIP_DEBUGF(IGMP_DEBUG, (") on if %p\n", netif));
			netif->igmp_mac_filter(netif, &allsystems, IGMP_ADD_MAC_FILTER);
		}

		return ERR_OK;
	}

	return ERR_MEM;
}

/**
 * Stop IGMP processing on interface
 *
 * @param netif network interface on which stop IGMP processing
 */
err_t igmp_stop(struct netif *netif)
{
	struct igmp_group *group = igmp_group_list;
	struct igmp_group *prev = NULL;
	struct igmp_group *next;

	/* look for groups joined on this interface further down the list */
	while (group != NULL) {
		next = group->next;
		/* is it a group joined on this interface? */
		if (group->netif == netif) {
			/* is it the first group of the list? */
			if (group == igmp_group_list) {
				igmp_group_list = next;
			}
			/* is there a "previous" group defined? */
			if (prev != NULL) {
				prev->next = next;
			}
			/* disable the group at the MAC level */
			if (netif->igmp_mac_filter != NULL) {
				LWIP_DEBUGF(IGMP_DEBUG, ("igmp_stop: igmp_mac_filter(DEL "));
				ip_addr_debug_print(IGMP_DEBUG, &group->group_address);
				LWIP_DEBUGF(IGMP_DEBUG, (") on if %p\n", netif));
				netif->igmp_mac_filter(netif, &(group->group_address), IGMP_DEL_MAC_FILTER);
			}
			/* free group */
			memp_free(MEMP_IGMP_GROUP, group);
		} else {
			/* change the "previous" */
			prev = group;
		}
		/* move to "next" */
		group = next;
	}
	return ERR_OK;
}

/**
 * Report IGMP memberships for this interface
 *
 * @param netif network interface on which report IGMP memberships
 */
void igmp_report_groups(struct netif *netif)
{
	struct igmp_group *group = igmp_group_list;

	LWIP_DEBUGF(IGMP_DEBUG, ("igmp_report_groups: sending IGMP reports on if %p\n", netif));

	while (group != NULL) {
		if (group->netif == netif) {
			igmp_delaying_member(group, IGMP_JOIN_DELAYING_MEMBER_TMR);
		}
		group = group->next;
	}
}

/**
 * Search for a group in the global igmp_group_list
 *
 * @param ifp the network interface for which to look
 * @param addr the group ip address to search for
 * @return a struct igmp_group* if the group has been found,
 *         NULL if the group wasn't found.
 */
struct igmp_group *igmp_lookfor_group(struct netif *ifp, ip_addr_t *addr)
{
	struct igmp_group *group = igmp_group_list;

	while (group != NULL) {
		if ((group->netif == ifp) && (ip_addr_cmp(&(group->group_address), addr))) {
			return group;
		}
		group = group->next;
	}

	/* to be clearer, we return NULL here instead of
	 * 'group' (which is also NULL at this point).
	 */
	return NULL;
}

/**
 * Search for a specific igmp group and create a new one if not found-
 *
 * @param ifp the network interface for which to look
 * @param addr the group ip address to search
 * @return a struct igmp_group*,
 *         NULL on memory error.
 */
struct igmp_group *igmp_lookup_group(struct netif *ifp, ip_addr_t *addr)
{
	struct igmp_group *group = igmp_group_list;

	/* Search if the group already exists */
	group = igmp_lookfor_group(ifp, addr);
	if (group != NULL) {
		/* Group already exists. */
		return group;
	}

	/* Group doesn't exist yet, create a new one */
	group = (struct igmp_group *)memp_malloc(MEMP_IGMP_GROUP);
	if (group != NULL) {
		group->netif = ifp;
		ip_addr_set(&(group->group_address), addr);
		group->timer = 0;		/* Not running */
		group->group_state = IGMP_GROUP_NON_MEMBER;
		group->last_reporter_flag = 0;
		group->use = 0;
		group->next = igmp_group_list;

		igmp_group_list = group;
	}

	LWIP_DEBUGF(IGMP_DEBUG, ("igmp_lookup_group: %sallocated a new group with address ", (group ? "" : "impossible to ")));
	ip_addr_debug_print(IGMP_DEBUG, addr);
	LWIP_DEBUGF(IGMP_DEBUG, (" on if %p\n", ifp));

	return group;
}

/**
 * Remove a group in the global igmp_group_list
 *
 * @param group the group to remove from the global igmp_group_list
 * @return ERR_OK if group was removed from the list, an err_t otherwise
 */
static err_t igmp_remove_group(struct igmp_group *group)
{
	err_t err = ERR_OK;

	/* Is it the first group? */
	if (igmp_group_list == group) {
		igmp_group_list = group->next;
	} else {
		/* look for group further down the list */
		struct igmp_group *tmpGroup;
		for (tmpGroup = igmp_group_list; tmpGroup != NULL; tmpGroup = tmpGroup->next) {
			if (tmpGroup->next == group) {
				tmpGroup->next = group->next;
				break;
			}
		}
		/* Group not found in the global igmp_group_list */
		if (tmpGroup == NULL) {
			err = ERR_ARG;
		}
	}
	/* free group */
	memp_free(MEMP_IGMP_GROUP, group);

	return err;
}

/**
 * Called from ip_input() if a new IGMP packet is received.
 *
 * @param p received igmp packet, p->payload pointing to the ip header
 * @param inp network interface on which the packet was received
 * @param dest destination ip address of the igmp packet
 */
void igmp_input(struct pbuf *p, struct netif *inp, ip_addr_t *dest)
{
	struct ip_hdr *iphdr;
	struct igmp_msg *igmp;
	struct igmp_group *group;
	struct igmp_group *groupref;

	IGMP_STATS_INC(igmp.recv);

	/* Note that the length CAN be greater than 8 but only 8 are used - All are included in the checksum */
	iphdr = (struct ip_hdr *)p->payload;
	if (pbuf_header(p, -(s16_t)(IPH_HL(iphdr) * 4)) || (p->len < IGMP_MINLEN)) {
		pbuf_free(p);
		IGMP_STATS_INC(igmp.lenerr);
		LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: length error\n"));
		return;
	}

	LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: message from "));
	ip_addr_debug_print(IGMP_DEBUG, &(iphdr->src));
	LWIP_DEBUGF(IGMP_DEBUG, (" to address "));
	ip_addr_debug_print(IGMP_DEBUG, &(iphdr->dest));
	LWIP_DEBUGF(IGMP_DEBUG, (" on if %p\n", inp));

	/* Now calculate and check the checksum */
	igmp = (struct igmp_msg *)p->payload;
	if (inet_chksum(igmp, p->len)) {
		pbuf_free(p);
		IGMP_STATS_INC(igmp.chkerr);
		LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: checksum error\n"));
		return;
	}

	/* Packet is ok so find an existing group */
	group = igmp_lookfor_group(inp, dest);	/* use the destination IP address of incoming packet */

	/* If group can be found or create... */
	if (!group) {
		pbuf_free(p);
		IGMP_STATS_INC(igmp.drop);
		LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: IGMP frame not for us\n"));
		return;
	}

	/* NOW ACT ON THE INCOMING MESSAGE TYPE... */
	switch (igmp->igmp_msgtype) {
	case IGMP_MEMB_QUERY: {
		/* IGMP_MEMB_QUERY to the "all systems" address ? */
		if ((ip_addr_cmp(dest, &allsystems)) && ip_addr_isany(&igmp->igmp_group_address)) {
			/* THIS IS THE GENERAL QUERY */
			LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: General IGMP_MEMB_QUERY on \"ALL SYSTEMS\" address (224.0.0.1) [igmp_maxresp=%i]\n", (int)(igmp->igmp_maxresp)));

			if (igmp->igmp_maxresp == 0) {
				IGMP_STATS_INC(igmp.rx_v1);
				LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: got an all hosts query with time== 0 - this is V1 and not implemented - treat as v2\n"));
				igmp->igmp_maxresp = IGMP_V1_DELAYING_MEMBER_TMR;
			} else {
				IGMP_STATS_INC(igmp.rx_general);
			}

			groupref = igmp_group_list;
			while (groupref) {
				/* Do not send messages on the all systems group address! */
				if ((groupref->netif == inp) && (!(ip_addr_cmp(&(groupref->group_address), &allsystems)))) {
					igmp_delaying_member(groupref, igmp->igmp_maxresp);
				}
				groupref = groupref->next;
			}
		} else {
			/* IGMP_MEMB_QUERY to a specific group ? */
			if (!ip_addr_isany(&igmp->igmp_group_address)) {
				LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: IGMP_MEMB_QUERY to a specific group "));
				ip_addr_debug_print(IGMP_DEBUG, &igmp->igmp_group_address);
				if (ip_addr_cmp(dest, &allsystems)) {
					ip_addr_t groupaddr;
					LWIP_DEBUGF(IGMP_DEBUG, (" using \"ALL SYSTEMS\" address (224.0.0.1) [igmp_maxresp=%i]\n", (int)(igmp->igmp_maxresp)));
					/* we first need to re-look for the group since we used dest last time */
					ip_addr_copy(groupaddr, igmp->igmp_group_address);
					group = igmp_lookfor_group(inp, &groupaddr);
				} else {
					LWIP_DEBUGF(IGMP_DEBUG, (" with the group address as destination [igmp_maxresp=%i]\n", (int)(igmp->igmp_maxresp)));
				}

				if (group != NULL) {
					IGMP_STATS_INC(igmp.rx_group);
					igmp_delaying_member(group, igmp->igmp_maxresp);
				} else {
					IGMP_STATS_INC(igmp.drop);
				}
			} else {
				IGMP_STATS_INC(igmp.proterr);
			}
		}
		break;
	}
	case IGMP_V2_MEMB_REPORT: {
		LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: IGMP_V2_MEMB_REPORT\n"));
		IGMP_STATS_INC(igmp.rx_report);
		if (group->group_state == IGMP_GROUP_DELAYING_MEMBER) {
			/* This is on a specific group we have already looked up */
			group->timer = 0;	/* stopped */
			group->group_state = IGMP_GROUP_IDLE_MEMBER;
			group->last_reporter_flag = 0;
		}
		break;
	}
	default: {
		LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: unexpected msg %d in state %d on group %p on if %p\n", igmp->igmp_msgtype, group->group_state, &group, group->netif));
		IGMP_STATS_INC(igmp.proterr);
		break;
	}
	}

	pbuf_free(p);
	return;
}

/**
 * Join a group on one network interface.
 *
 * @param ifaddr ip address of the network interface which should join a new group
 * @param groupaddr the ip address of the group which to join
 * @return ERR_OK if group was joined on the netif(s), an err_t otherwise
 */
err_t igmp_joingroup(ip_addr_t *ifaddr, ip_addr_t *groupaddr)
{
	err_t err = ERR_VAL;		/* no matching interface */
	struct igmp_group *group;
	struct netif *netif;

	/* make sure it is multicast address */
	LWIP_ERROR("igmp_joingroup: attempt to join non-multicast address", ip_addr_ismulticast(groupaddr), return ERR_VAL;);
	LWIP_ERROR("igmp_joingroup: attempt to join allsystems address", (!ip_addr_cmp(groupaddr, &allsystems)), return ERR_VAL;);

	/* loop through netif's */
	netif = netif_list;
	while (netif != NULL) {
		/* Should we join this interface ? */
		if ((netif->flags & NETIF_FLAG_IGMP) && ((ip_addr_isany(ifaddr) || ip_addr_cmp(&(netif->ip_addr), ifaddr)))) {
			LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup: attempt to join on interface %s", netif->name));
			/* find group or create a new one if not found */
			group = igmp_lookup_group(netif, groupaddr);

			if (group != NULL) {
				/* This should create a new group, check the state to make sure */
				if (group->group_state != IGMP_GROUP_NON_MEMBER) {
					LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup: join to group not in state IGMP_GROUP_NON_MEMBER\n"));
				} else {
					/* OK - it was new group */
					LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup: join to new group: "));
					ip_addr_debug_print(IGMP_DEBUG, groupaddr);
					LWIP_DEBUGF(IGMP_DEBUG, ("\n"));

					/* If first use of the group, allow the group at the MAC level */
					if ((group->use == 0) && (netif->igmp_mac_filter != NULL)) {
						LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup: igmp_mac_filter(ADD "));
						ip_addr_debug_print(IGMP_DEBUG, groupaddr);
						LWIP_DEBUGF(IGMP_DEBUG, (") on if %p\n", netif));
						netif->igmp_mac_filter(netif, groupaddr, IGMP_ADD_MAC_FILTER);
					}

					IGMP_STATS_INC(igmp.tx_join);
					igmp_send(group, IGMP_V2_MEMB_REPORT);

					igmp_start_timer(group, IGMP_JOIN_DELAYING_MEMBER_TMR);

					/* Need to work out where this timer comes from */
					group->group_state = IGMP_GROUP_DELAYING_MEMBER;
				}
				/* Increment group use */
				group->use++;
				/* Join on this interface */
				err = ERR_OK;
			} else {
				/* Return an error even if some network interfaces are joined */
				/** @todo undo any other netif already joined */
				LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup: Not enought memory to join to group\n"));
				return ERR_MEM;
			}
		}
		/* proceed to next network interface */
		netif = netif->next;
	}

	return err;
}

/**
 * Leave a group on one network interface.
 *
 * @param ifaddr ip address of the network interface which should leave a group
 * @param groupaddr the ip address of the group which to leave
 * @return ERR_OK if group was left on the netif(s), an err_t otherwise
 */
err_t igmp_leavegroup(ip_addr_t *ifaddr, ip_addr_t *groupaddr)
{
	err_t err = ERR_VAL;		/* no matching interface */
	struct igmp_group *group;
	struct netif *netif;

	/* make sure it is multicast address */
	LWIP_ERROR("igmp_leavegroup: attempt to leave non-multicast address", ip_addr_ismulticast(groupaddr), return ERR_VAL;);
	LWIP_ERROR("igmp_leavegroup: attempt to leave allsystems address", (!ip_addr_cmp(groupaddr, &allsystems)), return ERR_VAL;);

	/* loop through netif's */
	netif = netif_list;
	while (netif != NULL) {
		/* Should we leave this interface ? */
		if ((netif->flags & NETIF_FLAG_IGMP) && ((ip_addr_isany(ifaddr) || ip_addr_cmp(&(netif->ip_addr), ifaddr)))) {
			/* find group */
			group = igmp_lookfor_group(netif, groupaddr);

			if (group != NULL) {
				/* Only send a leave if the flag is set according to the state diagram */
				LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup: Leaving group: "));
				ip_addr_debug_print(IGMP_DEBUG, groupaddr);
				LWIP_DEBUGF(IGMP_DEBUG, ("\n"));

				/* If there is no other use of the group */
				if (group->use <= 1) {
					/* If we are the last reporter for this group */
					if (group->last_reporter_flag) {
						LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup: sending leaving group\n"));
						IGMP_STATS_INC(igmp.tx_leave);
						igmp_send(group, IGMP_LEAVE_GROUP);
					}

					/* Disable the group at the MAC level */
					if (netif->igmp_mac_filter != NULL) {
						LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup: igmp_mac_filter(DEL "));
						ip_addr_debug_print(IGMP_DEBUG, groupaddr);
						LWIP_DEBUGF(IGMP_DEBUG, (") on if %p\n", netif));
						netif->igmp_mac_filter(netif, groupaddr, IGMP_DEL_MAC_FILTER);
					}

					LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup: remove group: "));
					ip_addr_debug_print(IGMP_DEBUG, groupaddr);
					LWIP_DEBUGF(IGMP_DEBUG, ("\n"));

					/* Free the group */
					igmp_remove_group(group);
				} else {
					/* Decrement group use */
					group->use--;
				}
				/* Leave on this interface */
				err = ERR_OK;
			} else {
				/* It's not a fatal error on "leavegroup" */
				LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup: not member of group\n"));
			}
		}
		/* proceed to next network interface */
		netif = netif->next;
	}

	return err;
}

/**
 * The igmp timer function (both for NO_SYS=1 and =0)
 * Should be called every IGMP_TMR_INTERVAL milliseconds (100 ms is default).
 */
void igmp_tmr(void)
{
	struct igmp_group *group = igmp_group_list;

	while (group != NULL) {
		if (group->timer > 0) {
			group->timer--;
			if (group->timer == 0) {
				igmp_timeout(group);
			}
		}
		group = group->next;
	}
}

/**
 * Called if a timeout for one group is reached.
 * Sends a report for this group.
 *
 * @param group an igmp_group for which a timeout is reached
 */
static void igmp_timeout(struct igmp_group *group)
{
	/* If the state is IGMP_GROUP_DELAYING_MEMBER then we send a report for this group */
	if (group->group_state == IGMP_GROUP_DELAYING_MEMBER) {
		LWIP_DEBUGF(IGMP_DEBUG, ("igmp_timeout: report membership for group with address "));
		ip_addr_debug_print(IGMP_DEBUG, &(group->group_address));
		LWIP_DEBUGF(IGMP_DEBUG, (" on if %p\n", group->netif));

		IGMP_STATS_INC(igmp.tx_report);
		igmp_send(group, IGMP_V2_MEMB_REPORT);
	}
}

/**
 * Start a timer for an igmp group
 *
 * @param group the igmp_group for which to start a timer
 * @param max_time the time in multiples of IGMP_TMR_INTERVAL (decrease with
 *        every call to igmp_tmr())
 */
static void igmp_start_timer(struct igmp_group *group, u8_t max_time)
{
	/* ensure the input value is > 0 */
	if (max_time == 0) {
		max_time = 1;
	}
	/* ensure the random value is > 0 */
	group->timer = (LWIP_RAND() % (max_time - 1)) + 1;
}

/**
 * Delaying membership report for a group if necessary
 *
 * @param group the igmp_group for which "delaying" membership report
 * @param maxresp query delay
 */
static void igmp_delaying_member(struct igmp_group *group, u8_t maxresp)
{
	if ((group->group_state == IGMP_GROUP_IDLE_MEMBER) || ((group->group_state == IGMP_GROUP_DELAYING_MEMBER) && ((group->timer == 0) || (maxresp < group->timer)))) {
		igmp_start_timer(group, maxresp);
		group->group_state = IGMP_GROUP_DELAYING_MEMBER;
	}
}

/**
 * Sends an IP packet on a network interface. This function constructs the IP header
 * and calculates the IP header checksum. If the source IP address is NULL,
 * the IP address of the outgoing network interface is filled in as source address.
 *
 * @param p the packet to send (p->payload points to the data, e.g. next
 *            protocol header; if dest == IP_HDRINCL, p already includes an IP
 *            header and p->payload points to that IP header)
 * @param src the source IP address to send from (if src == IP_ADDR_ANY, the
 *         IP  address of the netif used to send is used as source address)
 * @param dest the destination IP address to send the packet to
 * @param ttl the TTL value to be set in the IP header
 * @param proto the PROTOCOL to be set in the IP header
 * @param netif the netif on which to send this packet
 * @return ERR_OK if the packet was sent OK
 *         ERR_BUF if p doesn't have enough space for IP/LINK headers
 *         returns errors returned by netif->output
 */
static err_t igmp_ip_output_if(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest, struct netif *netif)
{
	/* This is the "router alert" option */
	u16_t ra[2];
	ra[0] = PP_HTONS(ROUTER_ALERT);
	ra[1] = 0x0000;				/* Router shall examine packet */
	IGMP_STATS_INC(igmp.xmit);
	return ip_output_if_opt(p, src, dest, IGMP_TTL, 0, IP_PROTO_IGMP, netif, ra, ROUTER_ALERTLEN);
}

/**
 * Send an igmp packet to a specific group.
 *
 * @param group the group to which to send the packet
 * @param type the type of igmp packet to send
 */
static void igmp_send(struct igmp_group *group, u8_t type)
{
	struct pbuf *p = NULL;
	struct igmp_msg *igmp = NULL;
	ip_addr_t src = *IP_ADDR_ANY;
	ip_addr_t *dest = NULL;

	/* IP header + "router alert" option + IGMP header */
	p = pbuf_alloc(PBUF_TRANSPORT, IGMP_MINLEN, PBUF_RAM);

	if (p) {
		igmp = (struct igmp_msg *)p->payload;
		LWIP_ASSERT("igmp_send: check that first pbuf can hold struct igmp_msg", (p->len >= sizeof(struct igmp_msg)));
		ip_addr_copy(src, group->netif->ip_addr);

		if (type == IGMP_V2_MEMB_REPORT) {
			dest = &(group->group_address);
			ip_addr_copy(igmp->igmp_group_address, group->group_address);
			group->last_reporter_flag = 1;	/* Remember we were the last to report */
		} else {
			if (type == IGMP_LEAVE_GROUP) {
				dest = &allrouters;
				ip_addr_copy(igmp->igmp_group_address, group->group_address);
			}
		}

		if ((type == IGMP_V2_MEMB_REPORT) || (type == IGMP_LEAVE_GROUP)) {
			igmp->igmp_msgtype = type;
			igmp->igmp_maxresp = 0;
			igmp->igmp_checksum = 0;
			igmp->igmp_checksum = inet_chksum(igmp, IGMP_MINLEN);

			igmp_ip_output_if(p, &src, dest, group->netif);
		}

		pbuf_free(p);
	} else {
		LWIP_DEBUGF(IGMP_DEBUG, ("igmp_send: not enough memory for igmp_send\n"));
		IGMP_STATS_INC(igmp.memerr);
	}
}

#endif							/* LWIP_IGMP */
